WO1989004244A1

WO1989004244A1 - Method and apparatus for producing stretched film

Info

Publication number: WO1989004244A1
Application number: PCT/JP1988/001143
Authority: WO
Inventors: Hisashi Kojyou; Naoya Yamaguchi; Kazuhiro Tomoda; Tomoji Mizutani
Original assignee: Kohjin Co., Ltd.
Priority date: 1987-11-12
Filing date: 1988-11-12
Publication date: 1989-05-18
Also published as: AU615694B2; DE3885469D1; DE3885469T2; KR960015306B1; EP0399042B1; US4983337A; EP0399042A4; EP0399042A1; MX169882B; AU2622588A; KR890701335A

Abstract

This invention relates to a tubular stretching method for producing a stretched film by passing a tubular thermoplastic resin film between nip rollers having mutually different peripheral speeds and inflating the tube by the internal pressure under heating and a stretching apparatus to be employed therefor. The nip rollers consist at least of three sets of nip rollers, i.e. nip rollers R1 on the introduction side, nip rollers R2 at fold end portion after stretching and take-up nip rollers R3. A slit-like compressed air jet nozzle is disposed in the gap between a pair of rollers R2 and compressed air is jetted from this nozzle into a stretch portion bubble generated between R1 and R2 so as to inflate and stretch the bubble under heating. In this instance the compressed air is controlled either manually or automatically by sensing the bubble diameter in order to keep a desired bubble diameter, whenever necessary. After stretching, the tubular film is folded by a folding apparatus and is then guided into the nip rollers R2 and its both ends are cut open into two flat films by a film opening knife disposed inside or outside the nozzle between the nip rollers R2. Each flat film is then guided to right and left guide rollers and is taken up by the nip roller R3 after the slit-like jet nozzle and knife are withdrawn. The apparatus of the present invention can adjust either manually or automatically the bubble diameter and the inner pressure during tube stretching operation and can be used advantageously for tubular stretching of porous films.

Description

B / Tazashi Stretched film manufacturing method and manufacturing equipment

The present invention relates to a method and an apparatus for producing a stretched film by heating and stretching a thermoplastic tubular film, and more particularly, to a production method and a production method suitable for producing a tubular stretched film in which bubbles in a stretching portion are permeable. Connect to device. Background art

Generally, in manufacturing a tubular biaxially stretched film, a tubular unstretched film is passed between two pairs of nib rolls arranged at an appropriate distance, and a tubular unstretched film is formed between two pairs of nib rolls by a heating device attached thereto. This is done by heating at once and injecting compressed air to form a bubble, which is taken up by a lower nib roll via a group of folding rolls.

In general, the injection of compressed air is only the start, and after forming a bubble of a predetermined size, a certain amount of compressed air is sealed in the bubble by closing the lower nib roll, and stretching is continued. It is.

However, in the above-described method of manufacturing a biaxially stretched film that forms a bubble by enclosing air, bubbles are gradually reduced due to leakage of pressurized air from each of the upper and lower nib rolls, although a small amount during stretching. For this reason, the opening angle of the folding nib roll group is adjusted to prevent a decrease in the lateral magnification. However, when the opening angle of the folding nib roll group is adjusted, the stretching point may change and may not contribute to the increase in the lateral magnification. In addition, when a predetermined size of the pipe cannot be obtained by the operation at the start, it is necessary to repeat the start operation again, which is complicated. Furthermore, in the case of a breathable film, the internal air leaks from the film surface even if the upper and lower nib rolls are closed to contain the compressed air. After coming out, the pubble adjusted to a predetermined size gradually shrinks, making it impossible to surround biaxial stretching.

As a countermeasure for this, there is a method of injecting compressed air into the harbor. In the past, Japanese Patent Publication Nos. 33-3727 and 54-139965 have been proposed.

For example, in Japanese Patent Publication No. 33727/1987, a continuous circumferential groove is formed in the lower nib roll, and compressed air is supplied by a tubular piercing body through the groove. Because the film comes into contact, the film is easily deformed due to frictional force, and the portion of the film that is not contacted and sandwiched between needle rolls undergoes lateral stretching due to the diameter of the tubular abutting body, Problems such as poor uniformity of the whole film and deterioration of flatness occur.

Japanese Patent Application Laid-Open No. 54-139965 discloses a method in which a cut is made in the vicinity of the lower nip roll and a compressed air is supplied by injecting an air injection nozzle into the cut. It is more likely to puncture to make a nick. In particular, for films with low tear strength, the tearing part expands due to the stretching tension, making it impossible to cover the stretching. Disclosure of the invention

The present invention has been obtained as a result of intensive studies in order to solve the above drawbacks.That is, a tubular thermoplastic resin film is passed between nib rolls having different peripheral velocities, and the resulting purple is expanded by heating under internal pressure. At the time of producing a stretched film, it is difficult to find a tube-like stretching method and a device that can be used to supply compressed air from a nozzle in a purple pipe. The nip roll is composed of at least three sets of nip rolls of R1, R2 and R3. When the respective peripheral velocities are r1, r2 and r3, the ratio of rl Zr2 / r3 is 0.1. — Adjustable to 0.8 / 1 / 1-1.1, but

R 1 is the nibroll on the introduction side of the tubular unstretched film

R 2 is the nibroll at the end of folding after tubular stretching R 3 is a take-off nibroll following the end of folding

Pressurized air from the slit-shaped pressurized air blowing nozzle provided between the gaps between the pair of rolls of R2 into the expanded portion purple between R1 and R2, maintaining a predetermined bubble diameter if desired In order to perform this process, the compressed air that has been manually or automatically detected by detecting the bubble diameter is expanded and stretched while heating the compressed air by blowing out the supplied air, then folded by a folding device, and guided to the R2 nibroll, Both ends are cut into two flat films by a film cutting knife provided between two rolls of Nibble Roll R2, and each flat film is guided to the right and left guide rolls, and the slit is formed. The present invention relates to a method for producing a stretched film, which is characterized in that it is taken out by a nib roll R3 after bypassing a squirting nozzle and a cutting knife device, and an apparatus used for the same. That.

The apparatus and method of the present invention allow the internal pressure of the bubble to be adjusted automatically or automatically during the continuation of the tube stretching. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic view of an apparatus of the present invention and a view for explaining a situation where a tubular unstretched film is heated and expanded by using this apparatus.

FIG. 2 is a side view of the situation shown in FIG. 1 when the film cutting knife device is provided in the gap of the slit-shaped compressed air blowing device.

FIG. 3 is a structural explanatory view of the compressed air blowing nozzle device and the cutting knife device when the film cutting knife device is provided in the gap of the slit-shaped compressed air blowing device as viewed from the front.

FIG. 4 is an explanatory view of the structure of FIG. 3 as viewed from the side.

FIG. 5 is a side view of the situation shown in FIG. 1 when the film cutting knife device is provided at both ends of the nib roll with respect to the position of the slit-shaped compressed air blowing device. Fig. 6 is a structural explanatory view of a pressure air blowing nozzle device and a cutting knife device as viewed from the front when a film cutting knife device is provided at both ends of a nib roll with respect to a position of a slit-shaped pressure air blowing device. is there. FIG. 7 is an explanatory view of the structure of the photoelectric switch of the cutting knife section as viewed from above. BEST MODE FOR CARRYING OUT THE INVENTION

The present inventors have conducted intensive studies to solve the above-mentioned disadvantages, and as a result, have completed the present invention.

That is, the present invention relates to a method for producing a stretched film by passing a tubular thermoplastic resin film between nib rolls having different peripheral velocities and stretching the film by heating under an internal pressure, and an apparatus used therefor. The niff roll consists of at least three sets of nibs, Rl, R2 and R3. When the respective peripheral speeds are rl, r2 and r3, the ratio of r1Zr2 / r3 is obtained. It can be adjusted to 0.1-0.8 / 1/1-1.1, but

R 1 is the nibroll on the introduction side of the tubular unstretched film

R 2 is the nibroll at the end of folding after tubular stretching

R 3 is the take-off nip roll following the end of folding

And pressurized air from the slit-shaped pressurized air blowing nozzle provided between the gaps between the pair of rolls of R2 into the extended portion bubble between R1 and R2, and at this time, maintain a predetermined purple diameter if desired. In order to adjust the pressure, the compressed air, which can be changed manually or automatically by detecting the diameter of the bubble, is expanded and stretched under heating by the compressed air blown out and supplied, and then folded by a folding device. And cut both ends into two flat films with a film cutting knife provided between the two rolls of Nib Roll R2, and guide each flat film to the left and right guide rolls. The present invention also relates to a method for producing a stretched film and a device for use in the method, wherein the slit-like blowing nozzle and the knife device for censoring are removed and then taken up by a nib roll R3. According to the method and method of the present invention, the internal pressure of purple is also increased during the tube stretching. It can be adjusted manually or automatically, and it can be suitably carried out particularly in the case of tube-like stretching of a porous film.

The present invention will be described in more detail. 1 to 7 are examples of the device of the present invention, and are not limited to these examples as long as they have the function of the present invention.

Each symbol in the figure indicates the following part.

R 1 First nibble

R 2 Second nibble ''

R 3 Third nibble

1 Unstretched tubular film

2 Heater

3 Stretch bubble

4 Folding roll group

5, 5 'incision knife

6 Compressed air blowing nozzle

7 Stretched flat film

8, 8, Guide roll

9, 9 'Knife holder for censorship

1 0, 1 0, Compressed air leak prevention rod

1 1, 1 1, Knife holder moving motor

1 2 Pneumatic introduction pipe

1 3, 1 3, Threaded rotary axis

14 Compressed air injection nozzle device

15,5, bubble diameter detector

16, 16, screwed moving body

17, 17, bearing

1/8, 1/8, Holder support bar for incision knife

19, 19, mounting bracket

20, 23 Optical fiber

21, 22 Photoelectric switch 2 4 Photoelectric switch 8 Mounting bracket

2 5 Output controller

2 6 Automatic pneumatic supply valve

2 7 Compressed air supply blower

The apparatus according to the present invention is an apparatus for producing a stretched film by passing a tubular thermoplastic resin film between different nip rolls as shown in an explanatory view (FIG. 17), and performing a drawing by an internal pressure while heating to produce a stretched film. The wheel consists of at least three sets of nibbles R1, R2 and R3, where the ratio of r1 / r2 1 "3 is 0, where the peripheral velocities are r1, r2 and r3. 1-0.8 no 1 Z 1-1 · 1 can be adjusted in the range

R 1 is the nibroll on the introduction side of the tubular unstretched film

R 2 is the nibroll at the end of folding after tubular stretching

R 3 is the take-off nip roll following the end of folding

A heating device for heating the tubular film introduced between R 1 and R 2 and a folded g of the stretched tubular film, and the gap between the pair of rolls of the nipple R 2 is Adjustable, between the gears, a slit-shaped compressed air blowing nozzle device and two left and right film cutting knife devices that can move in the length direction of the nib roll R 2 are provided. Between R and R3, one or more for each flat film passage at a position where the two flat films 7, 7 'cut open can avoid the slit-shaped blowing nozzle device and the cutting knife device. An apparatus for producing a stretched film, comprising: two or more guide rolls (8, 8).

The compressed air blowing nozzle device 14 is composed of a compressed air blowing nozzle 6 and a compressed air introducing tube 12 as shown in FIGS. 3 and 6, and the nozzle 6 extends from between the gears of the Nipple R2 into the bubble 3. Supplying compressed air <The amount and pressure of compressed air is appropriate or the diameter of the bubble is detected. The bubble diameter detectors 15, 15, and the output controller 2 are automatically variable to maintain the specified purple diameter. 5, Automatic compressed air supply valve 26 and compressed air It is equipped with a supply probe '26.

Also, as shown in FIGS. 3 and 6, the crawler knife device is connected to the rotating shaft rotating motors 11 and 11 ′, and the rotating shaft 13 and the rotating shaft 13 are screwed in opposite directions. Can be moved to the left and right by the female screw which is paired with the male screw of 13 and 13. It is fixed to the knife holder 19, 9, and 9 provided on the moving body 16 and 16 In order to prevent the compressed air from leaking out from between the nozzle part and the knife holder in the case of the slitting knives 5, 5, and in the case of FIG. In FIG. 6, holder support rods 18 and 18 for the cutting knife are provided.

The nibroll R1 serves to seal the compressed air blown from the compressed air blowing nozzle 6 in the R2 portion of the tubular film at the upper portion, and has a peripheral speed 0.1 to 0.8 times the peripheral speed of the nibroll R2. Driven at speed. The peripheral speed ratio is determined by the desired stretch ratio. For example, in order to make the longitudinal magnification four times, the peripheral speed of the nib roll R 1 is set to 0.25 with respect to the nipper roll R 2. Adjust it.

In the case of FIG. 3, the gear between the pair of nib rolls R2 can be adjusted to, for example, 110 images, to the extent that the compressed air blowing nozzle 6 can be inserted in the gap (a). In the case of FIG. 6, it is sufficient that enough compressed air can be supplied into the bubble.

The nip roll R 3 has a role of picking up the two films 13 cut by the cutting knife 5 and is driven at a peripheral speed ratio of about 1 to 1.1 with respect to the peripheral speed of the nib roll R 2. Basically, the peripheral speed of the nib roll R 2 and the nib roll R 3 may be the same, but the film may sag due to the load of the guide rolls 8 and 8, etc. in taking up the film, and the peripheral speed of the nib roll R 3 These problems can be solved by making the film slightly faster and applying tension to the film.

The nip roll R 3 may separately take out two stretched flat films 7, 7, which are cut open as two pairs. The slit-shaped air blow nozzle 6 installed between the gaps (a) of the nib roll R 2 has a nozzle tip positioned near a line connecting the centers of the two rolls of the nib roll R 2, and a cut-out portion. The compressed air is blown into the elongate baffle according to the amount of air leaking from the airbag, etc., and has a role of holding a bubble of a predetermined size. The slit-shaped compressed air blowing nozzle 6 can be freely adjusted vertically with respect to the position of the nip roll R2.

The width (in the roll length direction) of the slit-shaped compressed air blowing nozzle 6 can be appropriately selected. However, as shown in FIG. 3, a film cutting knife device is provided in the gap of the slit-shaped compressed air blowing device. In this case, the nip roll is usually set to the length of the nip roll or longer than that, and as shown in Fig. 6, the film cutting knife device is provided at both ends of the nip roll with respect to the position of the slit-shaped compressed air blowing device. In this case, the width of the roll of the nozzle 6 in the length direction is set so that the film cutting knife when the space is moved to the minimum is within the folding diameter of the unstretched tube film to be used. '

As a method for allowing the film slitting knives 5, 5 to be movable, for example, a rotating shaft 13 is provided inside the slit-shaped pressurized air blowing nozzle 6, which is symmetrically threaded in opposite directions from the center, and this shaft is provided. 13 A knife holder 9 for incision with female threads for each male screw is attached to both sides of 3 and the rotating shaft 13 is rotated by the drive of the motor 11 so that the knife 5 for incision is symmetrical. You can move it. Of course, it is separated into 13 and 13 'around the rotation axis 13 and the motors 11 and 11 are connected to the left and right respectively, and the two cutting knives 5 and 5 are moved independently. You may be able to.

On the other hand, if the slit-shaped compressed air blowing nozzle 6 has a width equal to or less than the folding width of the unexpanded annular film 1 as in the case of FIG. 6, the cutting knives 5,5 and 5,5 are supported. The cleaving knife holders 19, 9 'are located on both outer sides of the slit-shaped pressurized air blowing nozzle 6, and are attached to the extension frame by a mounting bracket 19, 19, or the like. In the same manner as above, the incision knives 5, 5, Therefore, the rotating shaft 13 can be rotated to move in the length direction of the nib roll R2, and both ends can be cut open regardless of the width of the folded film during stretching.

In this case, the knife holders 9, 9 for incision are attached to the support rods 18, 18 so as not to rotate together with the rotation of the rotating shaft 13. In this case, it is preferable to provide bearings 17, 17 and the like so as to smoothly move in the longitudinal direction of the nib roll R2.

In order to automatically adjust the incision width at both ends of the foldable film during the stretching, the photoelectric switch is attached to the knife holders 9, 9, 9 by the mounting brackets 24, 24, respectively. The position of the knife holder can be automatically moved. The photoelectric switch of the present embodiment includes a light projecting unit 21 that emits a light beam guided by the optical fiber 120, a light receiving unit 22 that receives the light beam, an optical fiber 23 that guides the received light beam, and a relay. When the width of the film becomes smaller and the inner photoelectric switch, where the light was blocked by the film, began to receive the light, the switches of motors 11 and 11 'were turned on, and the rotating shafts 13 and 13 were rotated to make incisions. Move the knife holder inward.

Conversely, when the width of the film is widened and the outer photoelectric switch that received the light beam is blocked by the film that folded the light beam, the switches of motors 11, 11, and 11 enter and the rotating shafts 13, 13, are moved as described above. Rotate in the opposite direction to move the knife holder outward. In other words, the folded film end is moved so that it is always positioned between the inner and outer photoelectric switches, and the incision can be automatically continued without deviating from the incision knife width.

In the case of Fig. 3, that is, when the slit-shaped pressurized air blowing nozzle 6 is wider than the width of the folding film in the nibble roll R2, there are stretched bubbles to be blown on the outside of the left and right ends of the cutting knives 5,5,5. Since the compressed air blows unnecessarily out of the slit-shaped nozzle 6 toward the outside air, it has a larger diameter than the slit-shaped nozzle gap (a) and is about half the width of the slit-shaped compressed air blow-in nozzle 6 Cylindrical compressed air blowing By installing the control rod 10 on the left and right outer sides of the knife holders 9 and 9 and directly below the slit inside the slit-shaped compressed air blowing nozzle 6, the compressed air can be blown out of the bubble. Can be reduced. In this case, it is preferable that the compressed air blowing suppressing rods 10, 10, 10 are connected to the incision knife holders 9, 9 to move in conjunction with the knife holders 9, 9.

In addition, the width of the folded tubular film 3 to be cut is automatically detected by installing the diameter detectors 15 and 15 at the bottom of the pable, and the cutting knife 5 is moved to a position corresponding to this width. It can be automated as it can. Further, the fluctuation width of the bubble diameter can be reduced by linking the supplied compressed air amount with the stretchable bubble diameter detected by the bubble diameter detectors 15 and 15.

The supplied compressed air amount is automatically provided according to the stretched bubble diameter detected by the bubble diameter detectors 15 and 15 '. The purple diameter detector 15, 15, 15, irradiates visible light, infrared light, or a laser, and detects each light beam reflected and measures the distance to the reflecting object by using a measurement sensor that measures the distance from the object. It measures distance. The bubble diameter detectors 15 and 15 ′ can detect the distance to the bubble at the intermediate stage of the heater 2 by providing an observation hole at the lower portion of the heater 2 or in the heater 2. The output controller 25 calculates the diameter of the bubble based on the measurement distance obtained from two or more distance measurement sensors (Pubble diameter detectors 15, 15,) and supplies compressed air according to the difference from the set purple diameter. The opening degree of the valve 26 is adjusted to control the same purple diameter as the set purple diameter.

The compressed air supply valve 26 changes the valve opening degree according to a signal from the output controller 25 to adjust the amount of compressed air supplied from the blower 27.

In addition, another bubble diameter detector is provided just above the incision, and the lower bubble diameter is input to the output controller 25 so that compressed air can be supplied in consideration of the difference between the upper and lower purple diameters or the leakage at the incision. . The folding roll group 4 has a function of folding the stretched bubble film 3 and guiding it to the nibble roll R2. 6 and take-off nibroll smoothly without contacting the cutting knife device: has the function of leading to R3.

The unstretched film 1 is heated by a heater 2 installed so as to surround the annular stretched bubble in a ring shape, and is expanded by compressed air blown from a nozzle 6.

Furthermore, when the film is stretched in the longitudinal direction mainly due to the peripheral speed difference between the nib rolls R 1 and R 2, the film is simultaneously biaxially stretched. Of course, when the internal pressure is applied, longitudinal-axial stretching is also possible by setting the set diameter to be the same as that of the unstretched annular film 1. Example

Hereinafter, an example of the apparatus and the method for producing a stretched film of the present invention will be specifically described with reference to FIGS. 117 to 117 of the apparatus S. However, the present invention is not limited to the examples unless departing from the spirit of the present invention.

At the start-up, first, an unstretched tubular film containing 35% by weight of low-molecular-weight polyethylene thiophthalate (IV = 0.25) finely dispersed in linear low-density polyethylene (MI = 2.0) is nibroll R1, The unstretched tubular film 1 that has not started to heat and expand is passed through the folding roll group 4 and the nib roll R2, and the motors 11 and 11 connected to the rotating shafts 13 and 13 separated from each other. It is operated independently and is cut open by the cutting knives 5, 5, adjusted to the folding width of the unstretched tubular film 1, and made into two flat films 7, 7, and guide rolls 8, 7, 8, And with Nibroll R3.

Next, the unstretched tubular film 1 is heated by the heater 2, and compressed air is supplied from the compressed air blowing nozzle 6 into the tube 3 to form a bubble 3, and then the nibbles R 1 and R located above and below are formed. Drive 2 and adjust heating heater 2 and nib roll for nib roll R 2 The peripheral speed ratio of R1 is 0.31, the 緵 magnification is 0.2 times, and the compressed air volume is adjusted to 2.5 times the model magnification, and simultaneous biaxial stretching is performed to obtain a breathable biaxially stretched film 3. Manufactured. When the film 3 stretched by the above adjustment is folded by the folding roll group 4 and reaches the nib roll R2, the folding width of the pubble 3 gradually increases. By operating 1 and, the position of the incision knife 5 was gradually widened to the left and right, and the stretching and incision was continued smoothly.

Thereafter, the amount of compressed air to be supplied is adjusted so that the diameter of the stretched film 3 becomes substantially constant, and the stretched flat film 7, 7 'is cut open at the position of the nib roll R2 and the guide rolls 8, 8, 7 After the film was taken up by Nibroll R3, each flat film was separately wound up by two winders. The obtained biaxially stretched film 3 was a film having good air permeability and good flatness.

(Example 2).

The same unstretched annular film 1 as in Example 1 was passed through in the same manner as in Example 1 and taken out. Next, the unstretched annular film 1 was heated by the heater 2, and the bubble detectors 15 and 15, the main controller 25, the compressed air supply bubble 26, and the photoelectric switch and relay of the censor were operated.

Approximately one minute after the switch of the heater 2 was inserted, the drive motors of the nip rolls R1, R2R3 were switched on to start stretching. As the pulp gradually expanded, the opening of the compressed air supply valve 26 gradually decreased, and after about 5 minutes, it became the same as the set pulp diameter and stabilized. In the meantime, the incision nibs 5, 5, and were expanded by the operation of the photoelectric switch and the relay together with the expansion of the bubble, and the purple became stable and the operation frequency of the intermittent operation of the photoelectric switch was reduced and stabilized.

The stretched flat films 7, 7, which were cut open by the knives 5, 5 'at the position of the nib roll R2, were wound by a take-up winder in the same manner as in Example 1.

The obtained biaxially stretched film 3 was air permeable, but The bubbles were more stable, and the flat film that was cut open and wound was a film with a certain width and good flatness. Industrial applicability

The apparatus for producing a tubular stretched film of the present invention can supply compressed air from the nozzle of the slit-shaped compressed air blowing device provided between the gears of the nib roll R 2 even while the stretching is being performed, and thus leaks over time. Since the compressed air in the bubble can be replenished without stopping the stretching, the stretching at a constant stretching ratio can be continued for a long time. Furthermore, even when a porous film is produced by stretching a gas-permeable unstretched annular film or a non-stretched film that becomes gas-permeable by stretching, the air amount corresponding to the internal air leaking by ventilation is supplied by compressed air. The bubble diameter can always be kept constant, and a breathable stretched film can be manufactured stably for a long time.

Claims

Claim box

1. In a method of producing a stretched film by passing a tubular thermoplastic resin film between nib rolls having different peripheral speeds and expanding by heating under internal pressure to produce a stretched film, the nib roll has at least three sets of R1, R2 and R3. When the peripheral velocities are r1, r2 and r3, the ratio of r1 / r2r3 is 0 · 1—0.8 / 1Z1–1.1, and However

R 1 is the nibroll on the introduction side of the tubular unstretched film

R 2 is the nibroll at the end of folding after tubular stretching

R 3 is a take-off nibroll following the end of folding

A bubble generated by compressed air supplied by blowing compressed air from the slit-shaped compressed air blowing sootles provided between the pair of rolls of R2 into the extending portion purple between R1 and R2. Was expanded and stretched at least one time in the circumferential direction under heating, then folded by a folding device, guided to a nip roll R2, and both ends of the folded film were provided between the nip rolls. Cut two flat films with a film cutting knife, guide each flat film to the right and left guide rolls, bypass the slit-shaped blowing nozzle and cutting knife device, and then pull with a nib roll R3. A method for producing a stretched film.

2. The method for producing a stretched film according to claim 1, wherein the tubular thermoplastic resin film is a breathable film or a film which becomes breathable by stretching.

3. An apparatus for passing a tubular thermoplastic resin film between different nib rolls and expanding by heating under an internal pressure to produce a stretched film. The nib roll has at least three sets of R1, R2 and R3. When the peripheral velocities are r1, r2 and r3, the ratio of r1Zr2 / r3 is 0.1-0.8 / 1 / 1-1-1.1. Can be adjusted so that R 1 is the nibroll on the introduction side of the tubular unstretched film

R 2 is the nibroll at the end of folding after tubular stretching

R 3 is a take-off nibroll following the end of folding

A heating device for heating the tubular film introduced between R1 and R2, and a device for folding the stretched tubular film, and the gap between the pair of rolls of 2. Adjustable, between the gaps can be moved in the longitudinal direction of the R2 nibroll to cut both ends of the folded film and a slit-shaped compressed air blowing nozzle device that blows compressed air into the bubble In addition, two knife devices for cutting both ends of the film are provided on the left and right, and between R2 and R3, the two flat films that are cut open are the slit-shaped blowing nozzle device and the knife device for cutting. An apparatus for producing a stretched film, comprising one or more guide rolls in each of the flat film passages (2) at a position where the film roll can be avoided.

4. A manufacturing device for claim 3, characterized in that a film cutting knife device is provided in a gear of a slit-shaped compressed air blowing device.

5. A manufacturing apparatus for claim 3, wherein a knife device for cutting a film is provided on both ends of the Ep-roll with respect to a position of the slit-shaped compressed air blowing device.

6. Equipped with an automatic control device that can detect the bubble diameter of the amount and pressure of the compressed air blown out from the slit-shaped compressed air blowing nozzle and automatically change the pressure to eliminate it according to the fluctuation. Claim 3 characterized by the following.